Finger stop for a movable finger stop-type rotary dial

ABSTRACT

An improved finger stop arrangement for a rotary dial is disclosed wherein the movable finger stop includes two stop arms which are diametrically opposed about the axis of the dial. These arms cooperate with a pair of projections extending upward from the base plate of the dial and provide dual stopping means for the finger stop.

United States Patent i191 Blackmon, Jr.

[11'] 3, 1,11 Y Y [45] Nov. 26,1974

[ FINGER STOP FOR A MOVABLE FINGER [75] Inventor: Charles E. Blackmon,.lr.,

' Huntsville, Ala.

[73] Assignee: GTE Automatic Electric Laboratories Incorporated,Northlake, 111.

[22] Filed: July 9, 1973 [21] Appl. No.: 377,665

52 us. Cl. 179790 FW [51] Int. Cl. H04m 1/23 [58] Field of Search 179/90R, 90 FW, 90 A, 179/90 AT [5 6] References Cited UNITED STATES PATENTS2,905,766 9/1959 Soderbaum 179/90 R STOP-TYPE ROTARY DIAL 3,108,15910/1963 Mattke 179/90 R 3,391,245 7/1968 Dal Monte et a1 179/90 'R3,525,821 8/1970 Pulles 179/90 R Primary Exafniner-Wi1liam C. CooperAssistant Examiner-Gerald L. Brigance Attorney, Agent, or FirmDavid W,Hcid [57] ABSTRACT An improved finger stop arrangement for a rotary dialis disclosed wherein the movable finger stop includes two stop armswhich are diametrically opposed about the axis of the dial. These armscooperate with a pair of projections extending upward from the baseplate of the dial and provide dual stopping means for the finger stop.

4 Claims, 2 Drawing Figures Babb et a1 179/90 R SHEET 2 BF 2 PATENTELHSVZBISM FINGER STOP FOR A MOVABLE FINGER STOP-TYPE ROTARY DIALBACKGROUND OF THE INVENTION This invention relates generally to rotarydials used in telephone instruments, and more particularly to the typeof rotary dial in which the finger stop is movable within apredetermined angular range.

Rotary dials with a movable finger stop per se are well known in the artas is evidenced by US. Pat. No. 3,108,159 issued to C. F. Mattke on Oct.22, 1963, US. Pat No. 3,105,122 issued to J. G. Babb et al on Sept. 24,1963 and US. Pat. No. 3,525,821 issued to E. J. Pulles on Aug. 25, 1970.These dials have the advantage of 1 reduced size, which is accomplishedby eliminating much of the previously required space between thefingerholes for 1 and the and providing a movable finger stop so thatthe finger wheel may be rotated through an angle greater than 360. Themovable finger stop allows the dial shaft to be rotated more than 360and hence insures the necessary spacing between the consecutive impulseseries in the dial pulse signal train. With the advantage of reducedsize there is also the disadvantage of amore complex dial mechanism.

Since in all these prior art patents mentioned above the finger stop ismovable, it is important that the predetermined angle of movement of thefingerstop from its rest position to its fully rotated position belimited to insure that only the proper number of dial pulses will besent out over the telephone line. In some of the prior art dials it hasbeen found that the finger stop may be moved beyond the intendedpredetermined maximum rotation and hence the'dial rotated beyond itsintended degree of rotation. This results insendingout an incorrectnumber of dial pulses for the digit dialed since the finger wheel willbe moved through an angle greater than that which was set for the dialeddigit.

SUMMARY OF THE INVENTION As was indicated in the preceding discussion itis very important that the finger wheel be allowedto only rotate thepredetermined amount and hence not send out a false or incorrect seriesof dial pulses. In the present invention an improved finger stoparrangement is disclosed wherein primary and secondary fingerstop armscooperate with a pair of projections to insure that the finger stop andhence the finger wheel may not be rotated greater than the predeterminedangle.

The pair of stop arms of the finger stop in the present invention arelocated on opposite sides of the center of rotation and pivot point ofthe finger stop and hence any attempt to lift the finger stop over thecooperating projections for one of the arms will merely move the otherarm of the finger stop down even further into en- FIG. 2 is a top planview of the'rotary dial of the present invention withthe finger wheelremoved.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, there isillustrated,- in an exploded perspective view, the upper portion of atypical gagement with its corresponding stopping surfaces.

Hence it is impossible, short of destruction of the dial, to cause thefinger stop to override the stopping surfaces built into the dial. Thepresent invention may be advantageously employed in a miniature rotarydial of the general type illustrated in US. Pat. No. 3,525,821.

. BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an exploded view oftheupper portion of a rotary dial which incorporates the improvedfingerstop arrangement of the present invention.

rotary dial in which the present invention maybe incorporated. In theinterest of brevity, such items as the governor, impulsing contactsprings, dial shunting contact springs and other associated items havenot been shown since they form no part of the present invention. Theseand other necessary component parts of the rotary dial may be of thetype illustrated in US. Pat. No. 3,525,821 and fully and clearlydisclosed and described therein. Again referring to FIG. 1, the presentinvention will best be described by logical sequence in which the upperportion of the dial is assembled. First it will be noted that the mainshaft 1 extends from the lower portion of the dial, the components ofwhich have not been shown, up through aperture 2 in the mounting plate3, main shaft 1 serving to transmit the rotation of the finger wheel tothe usual components in the lower part of the dial. Onmounting plate 3there is included a pair of projections 4 and 5, these projectionsserving to limit the travel of finger stop 6- in addition to severalother functions which will be described subsequently. Projections 4 and5 are preferably made from molybdenum disulfide filled nylon. Numberplate 7 is positioned over mounting plate 3 and held into place thereonby means of locking ring 8 which is placed around projections 4 and 5 onthe top number plate 7 and then rotated with fingers 9 engaging notches10 of projections 4 and 5. Spiral main spring 11 is mounted withinprojections 4 and 5 resting on mounting plate 3, with its outer end 12engaging catch 13 located on the inner side of projection 4. Next hub 14is positioned within spring 11, withnotch l5 engaged by the inner end 16of the spring. Hub 14 is then rotated a predetermined number of turns inthe clockwise direction to pretension spring 11 and is then pushed downover the top of shaft 1, with the key portion of shaft 1 engaging thecorresponding portions of the center hub 14.

Coupling element 17 is then mounted over hub 14 with the inner keyportions 18 of coupling element 17 engaged by the outer key portions 19of hub 14. Movable finger stop 6 is then placed over, and rests on, the

outer flange of coupling element 17, with finger 20 10- cated on leftside of tab 21. Friction washer 22 is positioned over coupling element51 on top of finger stop 6 to frictionally couple the finger stop tocoupling element l7 and hence to dial shaft 11. Finger wheel 23 ismounted on coupling element 17 with legs 24 of coupling element 17engaging corresponding slots in finger wheel 23. A holding washer 25 is.positioned on finger wheel 23 with locking fingers 26 :at first restingon the top of legs 24.

C-shaped washer 27 is pressed into the keyed slot 28 of main shaft 1 tolock the assembly in position and then holding washer 25 is rotatedapproximately 60", as shown in FIG. 1. Fingers 26 now bear down ondepressions 29 of ridges 30 to permanently hold finger wheel 23,friction washer 22, finger stop 6 and coupling element 17 on hub 14. Acap 30 is mounted on top of finger wheel 23 with spring elements 31engaging corresponding slots 32 of finger wheel 23.

Also included on mounting plate 3 is a post 31 which cooperates withnotch 32 in number plate 7 to insure that number plate 7 is oriented inthe proper location. With finger stop 6 inserted in the proper positionthe primary arm portion 33 will be positioned between side 34 ofprojection 4 and side 35 of projection 5 and by virtue of main spring 11cooperating with the various coupling parts primary arm portion 33 willnormally rest against side 34. In this manner when the user rotatesfinger wheel 23 finger stop 6 will rotate from side 34 and its clockwiserotation be limited by side 35 of projection 5.

A secondary stopping arrangement has been included in finger stop 6 byvirtue of a secondary arm portion 36 of finger stop 6. This secondarystopping arrangement functions in conjunction with side 37 of projection4 and side 38 of projection 5. Thus, when the main spring 11 rotates hub14 and hence coupling element 17 counter clockwise the finger stop 7 byvirtue of finger 20 being on the left side of tab 21, is rotated in acounter clockwise direction such that primary arm portion 33 is urgedagainst side 34 and secondary arm portion 36 is urged against side 38 ofprojection 5. When the user rotates finger wheel 23 in the clockwisedirection to dial one of the digits, finger stop 6 will be also rotatedin a clockwise direction by virtue of the friction imparted to fingerstop 6 by friction washer 22 and the finger stop 6 will ultimately limitthe rotation of finger wheel 23 when the users finger contacts fingerstop 6 since the primary arm portion 33 will be urged into contact withside 35 of projection 5. The secondary stop will also come into playhere since secondary arm portion 36 will also come into contact withside 37 of projection 4 when the finger stop 6 has been rotated to itsfull clockwise direction. Should the user attempt to rotate the fingerwheel 23 an additional amount by attempting to lift finger stop 6 andhence move the primary arm portion 33 over the top edge of projection 5adjacent to side 35, this further clockwise rotation will be preventedby the intersection of secondary arm portion 36 against side 37projection 4. Since secondary arm 36 is located across the pivot pointof the dials center, when the finger stop 6 is lifted in an attempt toride up over the top of projection 5 this merely forces secondary armportion 36 down to insure that it will not ride over the top edge ofprojection 4 adjacent to side 37. Hence any attempt to override thefinger stop in the clockwise direction will be made even more difficultby this pivoting action which means that secondary arm portion 36 willbe securely stopped by side 37. In a similar fashion, if the userattempts to lift finger stop 6 over the projection 4 in the counterclockwise direction, the pivoting of finger stop 6 will merely placesecondary arm portion 36 further down and securely against side 38 ofprojection 5.

Hence it will be appreciated that by incorporating a second arm portioninto finger stop 6, it is virtually impossible for the user to overridethe stopping projections of the dial in either the clockwise or counterclockwise direction without virtually destroying the dial itself.

FIG. 2 is a top plan view of the dial in the assembled position andillustrates the relative locations of the various parts. As shown inFIG. 2, friction washer 22 and the dial components thereabove have beenremoved so that the relationship between the finger stop 6, projections4 and 5 with their sides 34, 37 and 35, 38 respectively is clearlyillustrated. Main spring 11 has been al lowed to rotate the assembly toits normal rest or most counter-clockwise positon.

What is claimed is:

1. In a rotary dial for a telephone, wherein said dial includes amounting plate having a pair of projections extending upward therefrom,and a finger wheel supported above said mounting plate for selectiverotation, the improvement comprising a movable finger stop cooperablewith said finger wheel for limiting the rotation of said finger wheel,said finger stop having a primary arm portion extending between firstspaced apart sides of said projections and into the area encompassed bysaid finger wheel and a secondary arm portion extending between secondspaced apart sides of said projections, whereby said first and secondsides of said projections in cooperation with said primary and secondaryarm portions respectively prevent said finger stop and hence said fingerwheel from being rotated in excess of a predetermined amount.

2. The improved rotary dial as claimed in claim 1 wherein said primaryand secondary arm portions lie in substantially the same plane.

3. The improved rotary dial as claimed in claim 1 wherein the minimumangle subtended between said primary and secondary arm portions is equalto or greater than 4. The improved rotary dial as claimed in claim 1wherein said projections are elongated, and curved with respect to theaxis of rotation of said finger wheel.

1. In a rotary dial for a telephone, wherein said dial includes amounting plate having a pair of projections extending upward therefrom,and a finger wheel supported above said mounting plate for selectiverotation, the improvement comprising a movable finger stop cooperablewith said finger wheel for limiting the rotation of said finger wheel,said finger stop having a primary arm portion extending between firstspaced apart sides of said projections and into the area encompassed bysaid finger wheel and a secondary arm portion extending between secondspaced apart sides of said projections, whereby said first And secondsides of said projections in cooperation with said primary and secondaryarm portions respectively prevent said finger stop and hence said fingerwheel from being rotated in excess of a predetermined amount.
 2. Theimproved rotary dial as claimed in claim 1 wherein said primary andsecondary arm portions lie in substantially the same plane.
 3. Theimproved rotary dial as claimed in claim 1 wherein the minimum anglesubtended between said primary and secondary arm portions is equal to orgreater than 90*.
 4. The improved rotary dial as claimed in claim 1wherein said projections are elongated, and curved with respect to theaxis of rotation of said finger wheel.